Circular knitting machines



Aug. 15, R. PEEL CIRCULAR KNITTING MACHINES Filed NOV. 10, 1960 FIG.2.

FIG. I.

INVENTOR;

ROBERT P EEL BY ATTYS.

United States Patent 2,995,913 CIRCULAR KNITTING MACHINES Robert Peel, Philadelphia, Pa., assignor to Singer-Fidelity, Inc., Philadelphia, Pa., a corporation of Delaware Filed Nov. 10, 1960, Ser. No. 68,460 4 Claims. (Cl. 66-149) The present invention relates to circular knitting machines, and more particularly to an improvement in machines for knitting ladies hosiery.

It is common practice in the art of circular knitting machines for hosiery and the like to employ a pneumatic take-up wherein a discharge tube, usually of plastic, is positioned to receive the tubular knit stocking as it passes downwardly through the cylinder of the circular knitting machine. A pneumatic take-up of this character serves the dual function of putting the proper tension on the stocking during the knitting operation and carrying away the finished product at the conclusion of the operation.

It has been found, however, that when knitting with nylon and other synthetic yarns, the stockings have a tendency to cling to the stationary discharge tube, causing that portion of the stocking to resist the rotation which the upper portion of the stocking is exposed to by reason of its being carried by the rotary needle cylinder. As a result, the stocking is twisted within the cylinder, exerting improper tension on the stocking and interfering with the proper knitting of the stocking by the needle cylinder and associated mechanism. Furthermore, the clinging of the stocking to the discharge tube also impairs the free travel of the stocking through the tube and sometimes causes temporary jam-ups of the stockings in the tube.

Many attempts have been made to eliminate the clinging of the stocking to the tube, for example, by applying an antistatic dressing on the yarn, using high relative humidity, or treating the surfaces of the tubing through which the fabric passes to render them antistatic. Such procedures have not been entirely satisfactory, and normally are only temporary in their action.

With the foregoing in mind, the present invention provides a novel means for eliminating the clinging of the stockings to the discharge tube.

More specifically, the present invention provides for elimination of such clinging by ionizing the air within the discharge tube whereby the static attraction of the stocking to the tube is substantially eliminated.

In the preferred embodiment of the invention, the air is ionized by a plurality of elements positioned in the discharge tube adjacent the lower end of the needle cylinder and connected to a power unit for energization.

All of the objects of the present invention and the various features and details of the construction and operation of the apparatus are more fully set forth hereinafter with reference to the accompanying drawing wherein:

FIG. 1 is a fragmentary sectional view of a circular knitting machine embodying the present invention;

FIG. 2 is in an enlarged transverse sectional view taken on the line 2-2 of FIG. 1; and

FIG. 3 is an enlarged sectional View taken on the line 33 of FIG. 1.

Referring now to the drawing, the illustrated embodiment of a knitting machine of the present invention comprises a frame having a hollow needle cylinder 11 mounted therein for rotation by a pair of gears 12 and 13. A fixed head 14 surrounds the upper end of the needle cylinder to support the sinkers, feed stations, and other knitting instrumentalities which cooperate with the needle cylinder in conventional manner to form the knitted fabric S. A dial cap 15 is mounted on a dial support bracket 16.

In the illustrated embodiment of the pneumatic take-up device, a fixed tube 21 is mounted on the frame '10 as indicated at 22 to project upwardly through the bore of the needle cylinder 11 having its outwardly-flared upper terminal end disposed immediately below the plane of the sinkers in the head 14. A discharge tube 24 is attached at its upper end to the lower terminal end of the cylinder tube 21 to receive the stocking S as the knitting thereof is completed. The opposite end of the discharge tube 24 is, in the present instance, connected to a suitable suction device (not shown) to cause the air to flow downwardly through the tubes 21 and 24. The invention is equally applicable to other pneumatic take-up devices, for example, such as that shown in U.S. Patent No. 2,873,596 to Larkin.

In accordance with the invention, means is provided to ionize the air in the discharge tube adjacent the needle cylinder. In the operation of a knitting machine embodying a pneumatic take-up, the air fiow through the discharge tube may be in the range of thirty to one-hundred cubic feet per minute, and by ionizing the air, charges of static electricity on the tube and the stocking are eliminated, thereby preventing clinging of the stocking to the tube with its concomitant disadvantages.

In the illustrated embodiment of the invention, the air in the discharge tube is ionized by a plurality of one point static bars 31 positioned at the upper end of the discharge tube 24 as shown in the drawing. In the drawing, there are three static bars mounted in a group in equally-spaced circumferential relation immediately adjacent the upper end of the discharge tube 24 and a fourth and fifth static bar in helical arrangement spaced below the upper group of static bars. In the present instance, each static bar 31 comprises an electrically-conductive cylindrical shell 41 having a central electrode 42 positioned in the shell and insulated therefrom, for example by a plug of insulating material 43. The shell 41 is grounded as indicated in FIG. 3, and the electrodes are connected in parallel by an electrical conduit 44 to a power unit 45 which likewise is grounded and is connected to a suitable source of electrical energy as indicated at 46. Preferably, the power unit supplies five to ten kilovolts of A.C. power having a frequency of 50 or 60 cycles. The power is supplied through high resistances, for example from three to five megohms, to the static bars so that in the event of the operator contacting the electrode of the static bar, the current is limited to one or two milliamperes which is not lethal. As shown in FIG. 2, the discharge tube 24 is of uniform internal diameter in the area of the static bars 31. In order to minimize the risk of operator contact with the electrode 42 and to insure against snagging of the knitted stocking S on the static bars 31, openings 47 are provided in the tube 24 which mount the cylindrical casings 41 in such a manner that they do not project into the interior of the tube, although the electrodes and the casings are open to the interior of the tube. In lieu of the static bars, it is possible to use a radio frequency generator with a reasonably high output voltage to discharge between an electrode and a grounded surface in the vicinity of the fabric. However, this is relatively expensive to manufacture and has high power consumption.

Thus, the present invention provides an effective arrangement in knitting machines for eliminating the difficulties which have arisen in the operation of knitting machines with pneumatic take-up devices. While a particular embodiment of the present invention has been herein illustrated and described, it is not intended to limit the invention to such disclosure, but changes and modifications may be made therein and thereto within the scope of the following claims.

I claim:

1. A circular knitting machine comprising a frame, a hollow needle cylinder mounted on said frame for rotation, means at the top of said cylinder cooperable therewith to form a knitted fabric and pneumatic take-up means including a stationary discharge tube mounted on said frame to extend below said cylinder in registry with the hollow bore thereof and operable to draw air and the knitted tube downwardly through said cylinder and said discharge tube, and means mounted adjacent the bottom of said cylinder to ionize the air flowing downwardly through said tube, to thereby eliminate static charge between said tube and said fabric.

2. A knit-ting machine according to claim 1 wherein said means to ionize the air comprises a plurality of static bars mounted in said tube immediately below said needle cylinder, each static bar comprising a grounded cylindrical shell, a central electrode mounted in said shell and insulated therefrom, and means to impress a high AC. voltage between said shell and said electrode, said elec- '4 trade and shell being open to the interior of said tube. 3. A knitting machine according to claim 2 wherein said tube is of uniform internal diameter in the area of said static bars and includes openings in the wall thereof, said static bars being mounted within the confines of said openings so as not to project into the interior of said tube.

4. A knitting machine according to claim 3 wherein a group of said static bars are mounted in equally-spaced circumferential relation at one level in said tube and a second group is disposed in helical arrangement spaced downwardly from said level.

References Cited in the file of this patent UNITED STATES PATENTS 2,873,596 Larkin Feb. 17, 1959 

